For motor vehicle brake systems it is important and necessary to know the state of the system as precisely as possible—and in particular as far as possible to know a position of actuating components, relevant for the build-up of brake pressure, at any given time. In motor vehicle brake systems having a pneumatic brake booster it is possible, for example, to use an instantaneous position of a moveable wall inside the brake booster, the position and movement of which is coupled to an actuating element, as a measure of the state of the system. The information obtained can be relayed to a control unit, a brake light switch or another unit in the form of electrical signals. Separate measuring devices are used for this purpose.
DE 103 51 933 A1, which is incorporated by reference, for example, discloses a pneumatic brake booster having a sensor device, which comprises a disk-shaped magnet as pickup element and a Hall sensor as sensor element, wherein the pickup element is moved together with the moveable wall and needs to be carried past the sensor element in order to register the position.
In addition to a greater outlay in terms of the manufacture, assembly, sealing and calibration to cater for the required measuring accuracy and durability, the complex construction of such units is generally seen as offering scope for improvement. Moreover, given the greater measuring range needed, such known measuring devices tend to take up more overall space and to increase the weight.